Causes and Effects of Design Change of Construction Projects

Abstract

Purpose: Design is the mother of all construction as it is not only technical but also strategic process for competitiveness. In last decade, enormous bridge projects have been designed in Nepal but not all of them have been implemented. The causes of bridge design changes, and their effects on projects in terms of cost and time schedule is found to be complex and are influenced by numerous interrelated factors. This research focuses on the causes, effects and impacts of design change/reviews in bridge projects designed and constructed under Bridge Branch, Department of Roads (DoR).

Design/Methodology/Approach: Five case studies were taken along with schedule questionnaire to contrast the causes, effects and impacts identified from questionnaire survey. The data obtained from the questionnaire were analyzed using the Relative Importance Index (RII) for finding the importance of each causes, effects, and impacts.

Findings/Result: The design change was found to be done mostly in the foundation of the bridges. Sometime the redesign was done for change in scope and location of the bridge due mostly due to social and political interference and interest rather than value engineering. The Consultant was the main origin agent for design changes of bridge projects as they were the most responsible for the detail survey, soil investigation and design and estimate of the bridge whereas the client found to be second origin agent for design change due to lack of required data, change of plans or scope. The major causes for the bridge design change were Non-complaint design with site requirement, Errors in design, Differing site conditions, unforeseen problems and Inadequate working details. The top three common effects of design changes are time overrun, cost overrun and requirement of additional specialist/equipment/personnel.

Originality/Value: It is basic research. This study helps in motivating and creating awareness among the design professionals working in design review which will create the influence to overcome issue of design change strategically.

Paper Type: Ex-Post Facto Research